Tuesday, April 30, 2013

Dog Health - Eye Disorders

American Pit Bull terriers are typically not prone to eye disorders, however terriers tend to be. The following is a list of common disorders and a brief description of each. For more information on these disorders and others that may be of concern be sure to talk with your veterinarian. Potential breeders should be tested for all eye disorders to prevent passing it onto future generations.


As with humans dogs can develop cataracts. Sometimes they are only slightly affected and have no interference with vision. If part of the lens is affected it can cause blurry vision. Loss of functional vision happens when a dog’s entire lens is clouded.

Nuclear Sclerosis

Often geriatric dogs form what’s called nuclear sclerosis in their eyes. After the age of eight years the lens hardens and causes a grayish color to the lens. This is a natural byproduct of age and typically inherited.  The sclerosis may either develop quickly within weeks or months or it can grow at a slower pace over years. This disorder can affect one or both eyes.

This disorder can affect diabetic dogs of any age as well as orphaned puppies that were raised on a milk supplement. Extreme heat, radiation, or chemicals can also cause this problem. Once it’s developed it’s not possible to clear the lens. In the past the outcome was blindness. However, now the same types of artificial lens replacement surgeries performed on humans are being done on dogs.

The procedure involves making a small incision in the eye and a hole in the small sac that holds the lens. A special probe then emulsifies ultrasonically removing the affected lens. An intraocular lens is then placed in the sac. Surgery is performed using a high magnified operating microscope. This artificial lens must match the original as close as possible. The procedure is finished with small sutures no larger than strands of hair. The downside to this procedure is that it doesn’t guarantee perfect vision, and only a limited amount of the artificial lens is available for dogs. Another issue that effects dogs more so then most humans is the inflammation after surgery tends to be greater accompanied with more scarring which can blur vision. The upside is if the lens isn’t perfect or isn’t able to be replaced the cornea is responsible for 2/3rd of the vision. This means that the functional vision shouldn’t be affected.

Lens Luxation

This disorder occurs when the fibers that hold the lens in place break it causes shifting, either backward or forward. Normal functions of the eye are interrupted and lead to glaucoma blindness. Symptoms may not appear until after three years depending on where the lens rests. Typically the first signs that there’s a problem is behavioral changes in the dog.  The pain may also cause a dog to paw at its eyes.

Primary lens luxation is when the disease is congenital. When this disorder happens from the result of injury to the lens it’s called a secondary lens luxation.

All cases require surgery and depending on how soon the condition was found will be the determining factor on how well treatment works. The entire lens is often replaced with an artificial one. Another process is removing part of the eye fluid causing the glaucoma. However, if the optic nerve is damaged there is no treatment available and the result is blindness. Damaged eyes are quite painful and to relieve the dog’s pain are either surgically removed or replaced with prosthesis.

Persistent pupillary membranes (PPM)
When the fetus is developing there’s vestiges of blood vessels. Generally by 4-5 months old these disappear. In some cases they remain and cause vision problems, some dogs have no problems. In extreme cases total or partial vision can be lost. Since an ophthalmic scope is needed typically an ophthalmologist would conduct the exam. Unfortunately unless cataracts form there are no treatments for this disorder.

Progressive retinal atrophy (PRA)

This inherited eye disorder is the result of vision cells degenerating. Blindness in the retina is the result. The early signs are loss of night vision causing the dog to possibly be reluctant to go outside or even in dark areas inside. Sadly after this day vision is also lost. Cataracts sometimes appear as well. Unfortunately there is no treatment for this condition. Like with PPM annual exams by veterinary ophthalmologist are needed.

Disclaimer – In no way am I claiming to be an expert on these topics. These are only informational articles written to help dog owners. It’s recommended that you always do your own research and consult with your veterinarian for more detailed information. (01-24-13)

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